1. Field of the Invention
The present invention relates to a signal processing method applied to a mobile communication system, and more particularly, to a method of segmenting to transfer a data block in MIMO (multi-input-multi-output) system and apparatus thereof.
2. Discussion of the Related Art
Generally, in mobile communication, it is known that MIMO (multi-input-multi-output) system is superior to a conventional unit-antenna system. Namely, in case of a rich scattering environment, the MIMO system shows the better performance than that of uni-to-uni antenna or uni-to-multi antennas.
In order for the MIMO system to operate more efficiently, there should be less correlation between signals received by a plurality of receiving antennas. One example of MIMO mobile communication system according to a related art is explained as follows.
FIG. 1 is a block diagram of V-BLAST (vertical Bell laboratories layered space time) system as one of MIMO systems.
Referring to FIG. 1, V-BLAST as a kind of MIMO system has M transmitting antennas 12 and N receiving antennas 16. The V-BLAST system enables to have M*N independent channels according to the number of antennas, thereby having a performance superior to that of a conventional uni-antenna system. A transmitting end of V-BLAST system separately transmits transmission data generated in sequence through M transmitting antennas.
Namely, the data 11 to be transferred pass a vector encoder 10. Signals inputted serially pass the vector encoder 10 to be converted to parallel signals. The serial-to-parallel converted signals are transmitted through M transmitting antennas. Generally, in order to enable parallel transmissions through the respective antennas, the MIMO system is designed to have the number of the receiving antennas 16 be greater than that of the transmitting antennas 12 (M<N).
The transmitting end individually transmits signals via the M antennas, and a receiving end individually receives the signals via the N antennas. Hence, the receiving antennas respectively receive the signals transmitted through the M transmitting antennas, and perform a predetermined algorithm on the received signals to detect the signals transmitted from the respective transmitting antennas. A signal processing unit 18 of the V-BLAST receiving end, as shown in FIG. 1, is for detecting signals, which were separately transmitted from the M antennas, from the receiving end.
The transmitting end of the V-BLAST system does not use a separate signal processing or space-time code. Namely, input signals are simply transmitted via the M antennas, respectively. And, the V-BLAST receiving end receives the signals, which were transmitted via the M transmitting antennas, through the N antennas, and detects the signals transmitted from the respective transmitting antennas using an appropriate signal processing algorithm.
A signal processing procedure in the receiving end is explained as follows. In detecting a signal transmitted via a specific transmitting antenna, signals transmitted from other transmitting antennas are handled as interference signals. Namely, the receiving end uses a method of computing weight vector of a receiving array antenna for each of the signals transmitted via the respective transmitting antennas and removing the influence of the previously detected signal. Meanwhile, the receiving end may use a method of detecting signals transmitted from the respective transmitting antennas in greater order of signal to interference noise ratio.
If the signals independently transmitted from the respective transmitting antennas enable to maintain their independency while passing a mobile communication channel 14, such a signal processing method is very efficient. Yet, there substantially exists a prescribed amount of correlation in a transmitting antenna array as well as a prescribed amount of correlation exists between the receiving antennas of a receiving antenna array. Hence, it is probable that independent channels as many as the product number (M*N) between the respective transmitting antennas and the respective receiving antennas may fail to be maintained.
In the MIMO system, the communication can be performed most efficiently in case that the receiving end receives the independently transmitted signals via the transmitting antennas to handle independently. Yet, if the independency of the respective channels is not guaranteed, it is difficult for the receiving end to separately detect the signal of the specific transmitting antenna. Hence, the specifically transmitted signal frequently causes errors to the receiving end.
As explained in the foregoing description, in case that the channel independency is broken as the input signals are simply transmitted via the respective antennas without using the separate signal processing or space-time code, the related art signal processing method in the MIMO system is unable to actively cope with such a variation.